The present invention relates to an apparatus for driving an electric motor according to a control command supplied from an external apparatus such as an external computer or the like so as to control at least one of the rotational position and rotational speed of the motor, and particularly relates to a motor driving control apparatus suitable for the driving control of a servomotor used in robots and various kinds of numerically controlled machine tools.
In general, in order to drive a servomotor used in robots and various kinds of machine tools, driving power is supplied to the motor through a servo amplifier and the result is fed back by means of an encoder so that motor control exactly corresponding to a control command given from the outside can be attained. An example of this type motor driving control apparatus can be found in Japanese Patent Unexamined Publication JP-A-62-193585.
In such a motor driving control apparatus, the control apparatus does not operate if no control command is supplied from the outside. In short, the motor cannot be driven without a control command.
Accordingly, it is difficult for the apparatus per se to judge whether or not the function thereof is kept normal.
In the above prior art, a test operation based on a feedback control pulse signal can be made. However, the prior art has no special consideration in making checking possible as to whether or not the function is normal with respect to the control command given from the outside. There arises therefore a problem in a complete function maintenance check of the apparatus which has been not yet installed in a robot, a machine tool or the like.